President Barack Obama declared Friday night that the capture of a second suspect in the Boston Marathon bombings "closed an important chapter in this tragedy." But he acknowledged that many unanswered questions remain about the motivations of the two men accused of perpetrating the attacks that unnerved the nation.
"The families of those killed so senselessly deserve answers," said Obama, who branded the suspects "terrorists."
The president spoke from the White House briefing room after 10 p.m. on the East Coast, just over an hour after law enforcement officials apprehended 19-year-old Dzhokhar Tsarnaev.
The suspect had been holed up in in a boat in a Watertown, Mass., neighborhood. His older brother, also a suspect in the bombings, was killed earlier Friday in an attempt to escape police, authorities said.
Obama said the nation owes a debt of gratitude to law enforcement officials and the people of Boston, a city paralyzed Friday by the manhunt for the two brothers.
"We will determine what happened," he said. "We will investigate any association that these terrorists may have had, and we'll continue to do whatever we have to do to keep our people safe."